1. Technical Field of the Invention
The present invention relates to a liquid crystal device board, a liquid crystal device, and an electronic apparatus, and more particularly, the present invention relates to a structure suitable for a transflective liquid crystal device.
2. Description of the Related Art
Hitherto, in known transflective liquid crystal display panels, both reflective display using external light and transmissive display using illuminating light such as backlight are made visible. Each of the transflective liquid crystal display panels has a reflective layer therein for reflecting external light and has a structure in which illuminating light such as backlight passes through the reflective layer. Some reflective layers of this type have one aperture (one slit) at each pixel of the liquid crystal display panel having a predetermined area.
FIG. 16 is a schematic sectional view schematically illustrating the schematic structure of a known transflective liquid crystal display panel 100. The liquid crystal display panel 100 has a structure in which a substrate 101 and a substrate 102 are bonded to each other with sealing adhesive 103 and liquid crystal 104 is infused between the substrates 101 and 102.
The substrate 101 has a reflective layer 111, having one aperture 111a at each pixel, formed on the inner surface thereof, and the reflective layer 111 has a color filter 112, having coloring layers 112r, 112g, and 112b and an overcoat layer 112p, formed thereon. The overcoat layer 112p on the color filter 112 has transparent electrodes 113 formed on the surface thereof.
On the other hand, the substrate 102 has transparent electrodes 121 formed on the inner surface thereof so as to intersect with the transparent electrodes 113 on the substrate 101 which faces the substrate 102. The transparent electrodes 113 above the substrate 101 and transparent electrodes 121 above the substrate 102 have an alignment film and a hard protective film formed thereon as necessary.
Also, the substrate 102 has a retardation film (¼ wave film) 105 and a polarizer 106 sequentially disposed on the outer surface thereof, and the substrate 101 has a retardation film (¼ wave film) 107 and a polarizer 108 sequentially disposed on the outer surface thereof.
When the liquid crystal display panel 100 having a structure as described above is installed in an electronic apparatus such a portable phone or a portable information terminal, the electronic apparatus has a backlight 109 behind the liquid crystal display panel 100. In the liquid crystal display panel 100, during the daytime or in a well-lighted area, e.g., in a building, reflective display is visible since external light is reflected off the reflective layer 111 after passing through the liquid crystal 104, again passes through the liquid crystal 104, and is emitted from the liquid crystal display panel 100 along a reflecting path R. On the other hand, at nighttime or in a dark area, e.g., in an open area, by illuminating the backlight 109, transmissive display is visible since, after passing through the apertures 111a, a part of illuminating light from the backlight 109 passes through the liquid crystal display panel 100 and then is emitted from the liquid crystal panel 100 along a transmitting path T.
However, in the known transflective liquid crystal display panel 100 described above, making the areas of the apertures of the reflective layer small so as to improve the brightness of the reflective display causes deteriorated brightness of the transmissive display. In particular, since transmitting light in the transmissive display passes through the liquid crystal layer only once while reflecting light visible in the reflective display passes through the liquid crystal layer twice, the transflective liquid crystal display panel 100 can not be optically constructed such that both reflected light and transmitted light are effectively used so that the two types of display mentioned above are clearly visible in the light transmissive state. For example, since the transflective liquid crystal display panel 100 is often constructed such that reflected light is effectively emitted from the liquid crystal display panel in the reflective display which is likely to become dark, the utilization efficiency of transmitted light (the ratio of the amount of light passing through and emitting from the liquid crystal display panel to the amount of light incident on the liquid crystal display panel) necessary to achieve the transmissive display is low, and thus the transmissive display becomes dark when the areas of the apertures of the reflective layer are excessively reduced as described above.
Accordingly, it is extremely difficult to construct the transflective liquid crystal display panel 100 so as to make both the reflective display and the transmissive display bright, that is, making the reflective display bright by reducing the areas of the apertures of the reflective layer requires the amount of illuminating light from the backlight to be sufficient enough so as to maintain the brightness of the transmissive display, thereby hampering the liquid crystal device to achieve a reduction in size, thickness, weight, and power consumption, which is essential to a portable electronic apparatus.
Also, since the brightness in the reflective display is in general insufficient as described above, the light transmission of the color filter 112 is required to be high so as to maintain the sufficiently bright display; however, this arrangement causes a problem in that sufficient chroma in the transmissive display obtained by light passing through the color filter only once is not achieved.
In view of the foregoing problems, one object of the present invention is to provide a liquid crystal device having a structure in which the brightness in reflective display and the brightness in transmissive display are achieved together in a higher dimension and in which the brightness in the reflective display and the chroma in the transmissive display are maintained together.